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This sample demonstrates the stateful behavior of a rule session through a simple shopping application which uses business rules. This sample should be deployed in a stateful axis2 session - i.e. session scope or transport scope.

Note

Before executing this sample, it is recommended that you refer to section Exposing Rules as Services which explains in detail the process of writing and deploying a business rule.

Sample Rule Definition

Rules

Rule 1: Apply 10% discount if total purchases is over 100.

Facts

There are two facts, which are "A customer made a purchase" and "a product is added".

package samples.shopping;

/**
 * Product
 */
public class Product {

    private String name;
    private float price;

    public String getName() {
        return name;
    }

    public float getPrice() {
        return price;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setPrice(float price) {
        this.price = price;
    }
}

package samples.shopping;

/**
 * Customer
 */
public class Customer {

    private String name;

    private int discount;

    public Customer(String name,
                    int discount) {
        this.name = name;
        this.discount = discount;
    }

    public String getName() {
        return name;
    }

    public int getDiscount() {
        return discount;
    }

    public void setDiscount(int discount) {
        this.discount = discount;
    }

    public void setName(String name) {
        this.name = name;
    }
}

package samples.shopping;

/**
 * Discount
 */
public class Discount {

    private Customer customer;
    private int amount;

    public Discount(Customer customer,
                    int amount) {
        this.customer = customer;
        this.amount = amount;
    }

    public Customer getCustomer() {
        return customer;
    }

    public int getAmount() {
        return amount;
    }

    public void setCustomer(Customer customer) {
        this.customer = customer;
    }

    public void setAmount(int amount) {
        this.amount = amount;
    }
}

package samples.shopping;

/**
 * Purchase
 */
public class Purchase {

    private String customer;
    private String product;

    public String getCustomer() {
        return customer;
    }

    public void setCustomer(String customer) {
        this.customer = customer;
    }

    public String getProduct() {
        return product;
    }

    public void setProduct(String product) {
        this.product = product;
    }
}

package samples.shopping;

/**
 * Purchase Log
 */
public class PurchaseLog {

    private String customer;

    private Product product;

    public PurchaseLog(String customer, Product product) {
        this.customer = customer;
        this.product = product;
    }

    public String getCustomer() {
        return customer;
    }

    public void setCustomer(String customer) {
        this.customer = customer;
    }

    public Product getProduct() {
        return product;
    }

    public void setProduct(Product product) {
        this.product = product;
    }
}

Rule Service Configuration (service.rsl)

An in-line rule set is used within the service.rsl file as follows.

<ruleService
        name="ShoppingService"
        xmlns="http://wso2.org/carbon/rules"
        targetNamespace="http://com.test/shopping"
	    scope="transportsession">
    <ruleSet>
        <rule resourceType="regular" sourceType="inline">
            <![CDATA[
                package shopping

                dialect "mvel"

                import samples.shopping.Customer;
                import samples.shopping.Product;
                import samples.shopping.Purchase;
                import samples.shopping.Discount;
                import samples.shopping.PurchaseLog;

                rule "Purchase notification new customer"
                    salience 11 no-loop true
                when
                    $p : Purchase()
                    not Customer(name == $p.customer)
                then
                    System.out.println( "New Customer : " + $p.customer);
                    insert(new Customer($p.customer, 0));
                end

                rule "Purchase notification"
                    salience 10 no-loop true
                when
                    $c : Customer()
                    $purchase : Purchase( customer == $c.name)
                    $product : Product( name == $purchase.product)
                then
                    insert(new PurchaseLog($c.name, $product));
                    modify($c){
                     setDiscount(0)
                    }
                    System.out.println( "Customer " + $c.name + " just purchased " + $product.name );
                end

                rule "Apply 10% discount if total purchases is over 100" salience 9  no-loop true dialect "java"
                    when
                            $p : Purchase()
                $c : Customer(name == $p.customer)
                $i : Double(doubleValue  > 100) from accumulate ( PurchaseLog( customer == $c.name, $price : product.price ),
                                                                            sum( $price ) )
                    then
                  $c.setDiscount( 10 );
                insert( new Discount($c, 10) );
                System.out.println( "Customer " + $c.getName() + " now has a shopping total of " + $i );
                end

                rule "cleanUp" salience 8
                when
                 $p : Purchase()
                then
                 retract($p);
                end
            ]]>
        </rule>
    </ruleSet>

 	<operation name="purchase">
        <input wrapperElementName="purchaseOrder" namespace="http://com.test/purchaseOrder">
            <fact elementName="purchase" namespace="http://com.test/purchaseOrder" type="samples.shopping.Purchase"></fact>
        </input>
        <output wrapperElementName="purchaseOrderRespone" namespace="http://com.test/purchaseOrder">
            <fact elementName="discount" namespace="http://com.test/purchaseOrder" type="samples.shopping.Discount"></fact>
        </output>
    </operation>
    <operation name="addProduct">
        <input wrapperElementName="addProduct" namespace="http://com.test/addProduct">
            <fact elementName="addProduct" namespace="http://com.test/addProduct" type="samples.shopping.Product"></fact>
        </input>
    </operation>
</ruleService>

Axis2 Service Configuration (services.xml)

<service name="ShoppingService" scope="transportsession">   
    <operation name="purchase"/>
    <operation name="addProduct" mep="http://www.w3.org/ns/wsdl/in-only"/>
</service>

Deploying and Testing the Service

1. Deploy the rule service through the BRS management console. You can follow either of the two methods:

  • Bundle all artifacts in an .aar file and upload it (Rule Service -> Upload menu).
  • Create using the Rule Service wizard UI (Rule Service -> Create menu).

The above steps are discussed in detail in section Exposing Rules as Services.

2. After deployment, the service will appear in the "Deployed Services" window of the BRS management console. Access the service's dashboard by clicking on it.

3. In the "Client Operations" widget of the dashboard, invoke the Try-it tool to test the service.

4. In the service's TryIt window, issue a request similar to the following. First add a product before buying it.

Adding a product:

<name>product name</name>
<price>12.34</price>

Doing a purchase:

<customer>your name </customer>
<product>product name</product>

5. Alternatively, you can use code generation link in the  "Client Operations" widget of the dashboard to invoke the service. However, in the axis2 stub-based clients, there is a limitation in managing session with in-only operations such as 'addProduct'. Therefore, prior to use the code generation, you have to remove mep=http://www.w3.org/ns/wsdl/in-only from the service xml and redeploy the service. This makes the 'addProduct' method return an empty result.

A client using generated stub codes is shown below where the codes were generated with option "Unpacks the databinding classes".

package org.wso2.carbon.samples;

import org.apache.axis2.AxisFault;
import org.wso2.carbon.samples.shoppingService.product.AddProduct;
import org.wso2.carbon.samples.shoppingService.product.Product;
import org.wso2.carbon.samples.shoppingService.purchaseOrder.Discount;
import org.wso2.carbon.samples.shoppingService.purchaseOrder.Purchase;
import org.wso2.carbon.samples.shoppingService.purchaseOrder.PurchaseOrder;
import org.wso2.carbon.samples.shoppingService.stub.ShoppingServiceStub;
import java.rmi.RemoteException;

public class ShoppingServiceTestCase {

    public static void main(String[] args) {

        ShoppingServiceStub shoppingServiceStub = null;
        try {
            shoppingServiceStub = new ShoppingServiceStub("http://localhost:9763/services/ShoppingService");
            shoppingServiceStub._getServiceClient().getOptions().setManageSession(true);

            AddProduct addProduct = new AddProduct();
            Product product = new Product();
            product.setName("toy");
            product.setPrice(200);
            Product[] products = new Product[1];
            products[0] = product;

            shoppingServiceStub.addProduct(products);

            PurchaseOrder purchaseOrder = new PurchaseOrder();
            Purchase purchase = new Purchase();
            purchase.setCustomer("Ishara");
            purchase.setProduct("toy");

            Purchase[] purchases = new Purchase[1];
            purchases[0] = purchase;

            purchaseOrder.setPurchase(purchases);
            Discount[] discounts = shoppingServiceStub.purchase(purchases);
            int result = discounts[0].getAmount();
            System.out.println(result);

        } catch (AxisFault axisFault) {
            axisFault.printStackTrace();
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }
}
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